1. Field of the Invention
The present invention relates to an optical pickup device, a recording/reproducing apparatus, and a recording/reproducing method, and more particularly to an optical pickup device, a recording/reproducing apparatus, and a recording/reproducing method, which are available for a recording medium equipped with a plurality of record layers.
2. Discussion of the Related Art
Generally, a recording/reproducing apparatus records/reproduces data in/from a recording medium using an optical signal and information of various disc types. Recently, with the increasing development of a new technique capable of processing high-quality moving images or another technique capable of compressing such moving images, the demand of developing a high-density recording medium rapidly increases.
For this purpose, there has recently been developed a variety of high-density recording medium technologies, for example, a Blu-ray Disc (BD) based on a short-wavelength blue ray, a high-density DVD (HD-DVD), and a near field recording (NFR) unit based on near field optics.
In order to effectively record/reproduce data in/from the above-mentioned high-density disc, the high-density disc has been designed to have a plurality of record layers. Therefore, there is needed a method for effectively accessing the above record layers.
A data transfer rate (DTR) must be guaranteed as an effective optical system for processing a large amount of data. In this case, increasing a rotation speed of the recording medium is physically limited, such that a method for increasing the data transfer rate using multiple optical signals is needed.
Also, the near field recording (NFR) device uses a lens having near-field characteristics. As a result, there is needed a method for allowing the above-mentioned near field recording (NFR) device to be compatible with the conventional recording medium.